Radio continuum , Spitzer infrared , optical , and XMM-Newton X-ray and ultraviolet observations ( UVW 1 and UVM 2 ) are used to study large–scale shock fronts , young star complexes , and the galactic nuclei in the interacting galaxies NGC 2207/IC 2163 .
There are two types of large–scale shock fronts in this galaxy pair .
The large-scale shock front along the rim of the ocular oval in IC 2163 has produced vigorous star formation in a dusty environment , bright in the Spitzer 8 µm and 24 µm images .
This large-scale shock lies behind NGC 2207 and is not prominent in X-rays .
In the outer part of the companion side of NGC 2207 , a large-scale front attributed to disk or halo scraping is particularly bright in the \lambda 6 cm and \lambda 20 cm radio continuum but not in any tracers of recent star formation ( H \alpha , 8 µm , 24 µm , or ultraviolet emission ) or in X-rays .
This radio-continuum front is simply due to compression of the magnetic field and may be mainly in the halo on the back side of NGC 2207 , between the two galaxies .
Values of the ratio of 8 µm to \lambda 6 cm radio continuum flux density of prominent , kpc-sized , Spitzer IRAC star-forming clumps in NGC 2207/IC 2163 are compared with those of giant radio H II regions in M81 .
For the bright clumps in NGC 2207 , the mean value of this ratio is the same as for the M81 H II regions , whereas for the bright clumps on the rim of the IC 2163 ocular oval , the mean value is nearly a factor of two greater .
On the other hand , the galaxy pair has global values of the ratios of infrared to radio continuum flux density in the Spitzer 8 µm , 24 µm , and 70 µm bands and the IRAS FIR significantly below the medians/means for large samples of galaxies . Feature i , a mini-starburst on an outer arm of NGC 2207 on its anti-companion side , is the most luminous 8 \mu m , 24 \mu m , 70 \mu m , radio continuum , and H \alpha source in the galaxy pair .
Highly absorbed , it is not detected in X-rays and is fainter in the ultraviolet than the clump containing SN 1999ec , 8″ SSE of the core of feature i .
We find evidence that a radio supernova was present in the core of feature i in 2001 .
X-ray emission is detected from the nucleus of NGC 2207 and from nine discrete sources whose X-ray luminosities make them possible candidates for ULXs .
One of these corresponds with the Type Ib SN 1999ec , and another may be a radio supernova or a background quasar .
The X-ray luminosity of the NGC 2207 nucleus is log L _ { 0.3 - 10.0 keV } = 40.6 [ ergs s ^ { -1 } ] , which , together with its X-ray spectrum , suggests that this is a highly absorbed , low-luminosity , Active Galactic Nucleus .